JavaScript Obfuscator - JavaScript Obfuscator is a free online tool that obfuscates your source code, preventing it from being stolen and used without permission.
DomainLockJS - Free code snippet to lock javascript files to your domain. Protect javascript code. Easy cut & paste script. Prevent unauthorized use of your scripts and deter code theft.
Terser - JavaScript parser, mangler, optimizer and beautifier toolkit for ES6+
UglifyJS - JavaScript minifier, beautifier, mangler and parser toolkit.
Closure Compiler - The Closure Compiler is a tool for making JavaScript download and run faster.
YUI Compressor - Yahoo JS/CSS Compressor